Collection of oils

ABSTRACT

Oils, particularly petroleum oils may be removed from water, from beaches and from wildlife, by contacting the oils with a collector comprising granular polyurethane particles substantially devoid of cellular structure. Preferably the collector particles are of a jagged, spiny, cragged nature. When applied to an oil contaminant, the collector particles agglomerate the oil into a gel which can be skimmed or otherwise removed easily.

United States Patent Strickman {4 1 Apr. 18, 1972 54] COLLECTION OF OILS3,352,778 1 1/1967 Brink et al. ..210/23 Inventor: Robe" L. Strkkmm,River vale, NJ 3,494,862 2/1970 Horowitz ..210/40 [73] Assignee:Strickman Industries, Inc., Orangeburg, OTHER PUBLICATIONS N,Y, Chemicaland Engineering News, July l, 1968, Pages 46- 47.

[22] Filed: July Primary Examiner-Reuben Friedman 21 A I. N I; 55 243Assistant Examiner-Thomas G. Wyse l 1 PP 1 Anamey-Hane, Baxley 8LSpiecens Related [1.5. Application Data [57] ABSTRACT [63]Continuation-impart of Ser. No. 868,9!6, Oct. 23,

I969 OllS, particularly petroleum oils may be removed from water, frombeaches and from wlldhfe, by contacting the 0118 with a collectorcomprising granular polyurethane particles substan- [szl 2 2] tiallydevoid ofcellular structure. Preferably the collector par- [5 l Ill!-Cl. ..C0 '3 9/02 tides are of a j g spiny, cragged Hanna w applied [0[53] Field "210/401 21 an oil contaminant, the collector particlesagglomerate the oil into a gel which can be skimmed or otherwise removedeasily. [56] References Cited 1 Claims, No Drawings UNITED STATESPATENTS 3.334942 8/1967 Teitsma ..2 l0/DlG. 21

COLLECTION or OILS CROSS REFERENCE TO RELATED APPLICATION This is acontinuation-in-part application based on U.S. Pat. application 868,9 l6 filed Oct. 23, 1969.

BACKGROUND OF INVENTION with ever-increasing sizes of modern tankers andfacilities for cleaning and servicing them, there is a stepped-up riskof pollution resulting from leakage and/or spillage. A case in point wasthe Torrey Canyon disaster of I967 wherein some of England's mostbeautiful beaches were subjected to catastrophic pollution by oilslicks.

In offshore drilling for petroleum there is an ever-present danger thatrock fissures, faults or movements of geological formations may releasemassive doses of polluting petroleum oils. The beaches of Santa Barbara,California, were polluted by petroleum oils released via fissures whichdeveloped during offshore drilling. Even as late as 1969, at SantaBarbara, straw had to be used to mop up the oil slicks.

Detergents or dispersants such as that marketed by Imperial ChemicalIndustries, Ltd. under the trademark Dispersof, serve to split up suchoil slicks but do not remove them.

A discussion of problems in dealing with oil pollution on sea and landwas presented by J. W. Smith (of Warren Spring Laboratory, Stevenage,Herts, England) in Vol. 54 No. 539 of the Journal of the Institute ofPetroleum (Nov. 1968) wherein a number of solutions to these problemswere presented. One proposed solution was to absorb oil contaminants onfragments of polyethylene or polyurethane foam. These very lightsponge-type hydrophobic materials float and are wetted readi' ly by oil.But although when spread over floating oil they rapidly absorb the oil,the oil still floats. Smith also suggested that it might be possible tospray something on the oil which would cause it to gel or coagulate andso simplify collection; however no means or materials were suggested foreffecting such gelation,

SUMMARY Accordingly, it is an object of the present invention to providea process for removing pollutant oils, particularly petroleum oils, fromthe sea or from waterways or from beaches or other occurrences byeffecting gelation of the oils.

It is still another object of the present invention to provide a processwhich accomplishes oil-water separation, not as a liquid-liquidseparation, but as a liquid-solid separation; whereby skimming,screening or other known techniques of liquid-solid separation may beused to remove the gelled oil.

It is still another object of the present invention to provide a processfor removing an oil slick from a beach, and in which the collectormaterial may be applicable to the beach, either before or aftercontamination by the oil slick.

It is still another object of the present invention to provide a processfor reclaiming oil from sands, for example in in the vicinity ofoilwells.

It is still another object of the present invention to provide a processfor removing oils from food products.

It is still another object of the present invention to provide asuitable collector material for use in the foregoing processes.

It is still another object of the present invention to provide asuitable collector material which reduces the area covered by an oilslick and prevents leakage of the slick through breaks in a confiningboom.

It is still another object of the present invention to provide amaterial which can gel whole tank fulls of oil to prevent the oil'sdissemination into a slick.

It is still another object ofthe present invention to provide acollector material which operates on contact with an oil and which canbe handled safely and conveniently.

It is still another object of the present invention to provide acollector material which may be used safely in contact with wildlifesuch as fish, birds, shellfish and mammals to remove oil contaminationstherefrom.

It is still another object of the present invention to provide acollector material which can be used, in conjunction with one or moreother filtering materials, to serve as a final filtering medium.

It is still another object of the present invention to provide acollector material which can be used in filtering systems, such as thoseused in cleaning ship's bilges, for separation of oils from detergentsolutions or the like.

It is still another object of the present invention to provide acollector material which may be reused and from which the gelled oilscan be removed by simple mechanical pressing.

it is still another object of the present invention to provide a processfor increasing absorptiveness of polyurethane foams by contacting themwith water.

It is still another object of the present invention to provide a processfor preparing the collector material.

The foregoing and other objects will be seen from the detaileddescription of the invention which follows.

The collector material of the present invention comprises a particulatepolyurethane which is substantially devoid of cellular structure and, ina preferred embodiment, is rigid and composed of granules which are of ajagged, spiny, cragged nature. The preferred polyurethanes, ascontemplated by the invention are characterized by having sufficientrigidity at am bient temperatures so that they may be granulated inconventional equipment.

The particulate collector material of the invention is desirably of aparticle size which is preponderantly below about 1,500 microns andpreferably between about 50 to 750 microns.

The polyurethanes which comprise the collector material of the inventionare those conventionally obtained by the reaction of polyisocyanateswith polyols. The polyols employed as starting materials are preferablypredominantly polymeric. The rigidity of the polyurethanes, as wellrecognized by the polymer chemist, depends upon the existence ofcrosslinks between the molecules and crosslinking is obtained byemploying starting materials having a reaction functionality greaterthan two. Most commonly, this higher functionality is found in thepolyol component, but more recently polyisocyanates have beencommercially available having the functionality of greater than two.

Practically any polyol which, when reacted with a polyisocyanate,produces a polyurethane and preferably a rigid polyurethane, may beemployed. Among the preferred polyols are the polyether polyols, andespecially the reaction products of propylene oxide withlow-molecular-weight compounds having two or more hydroxyl groups, suchas ethylene glycol, propylene glycol, butanediol, diethylene glycol,dipropylene glycol, triethylene glycol, polyethylene glycol, glycerol,hexanetriol, trimethylolpropane, pentaerythritol, methylglycoside,sorbitol, mannital, glucose, sucrose, etc.

Additional polyols which may be employed with a polyisocyanate toproduce the polyurethanes are: polyethylene glycol having molecularweights of 400 and 3,000, tripropylene glycol, l,4-butanediol,thiodiglycol, hexanediol, neopentyl glycol, glycerol, trimethylolethane,trimethylolphenol, starch, cellulox, polycaprolactone, castor oil,glycerine ethylene oxide adducts, ethylene oxide and mixed ethyleneoxidepropylene oxide adducts of the polyols cited, mixed ethyleneglycol-propylene glycol adipate resin (molecular weight L900polyethylene adipate, etc.

Instead of polyether polyols, there may be employedpolyhydroxyl-terminated polyesters, preferably those derived at least inpart from triols or higher polyols. The polyester polyols are usuallyless advantageous than the polyether polyols because they are generallymore expensive and more viscous. Among the acids that may be used tomake up the preferred polyesters are any of the polycarboxylic acidssuch as malonic, succinic, adipic, maleic, phthalic, isophthalic,fumaric, oxalic, sebacic, dimerized lineleic or chlorendic together withany of the polyols described above.

Polyols are usually referred to in terms of their hydroxyl number.Polyols having a high hydroxyl number (above 300 are preferred when arigid polyurethane is desired, particularly polyols other than simple,non-polymeric polyols. Hydroxyl numbers which are between about 300 and800 are most desirable. At the higher hydroxyl numbers, a more friable,but also a less dimensionally stable expanded polyurethane results.

Any polyisocyanate which will give a polymer with a suitable polyol maybe employed, but a polyisocyanate which is a liquid at the temperatureof reaction, i.e., at between about l5 and 90 C. and particularlybetween about and 50 C. is preferred. Particularly useful is the widelyused tolylene diisocyanate (TDI) sold commercially as the 80:20 or 65:35mixture of 2,4,:2,6 isomers. Also suitable are p,p'-diphenyl methanediisocyanate (MD!) and its crude grade (PP!) and polymethylenepolyphenyl isocyanate (a mixture sold under the tradename PAPI). Otherpolyisocyanates which can be employed are: dianisidine diisocyanate,xylylene diisocyanate, diphenyl sulfone diisocyanate, 4-chloro-1,3-phenylene-diisocyanate; 4-isopropyl- 1,3-phenylene diisocyanate;2,4-diisocyanatodiphenylether; 3,3-dimethyl-4,4-diisocyanatodiphenylmethane; mesitylene diisocyanate;4,4-diisocyanatodibenzyl; 1,5-naphthalene diisocyanate; 3,3- bitolylene-4,4'-diisocyanate; triphenylmethane triisocyanate, tritolylmethanetriisocyanate, tetramethylene diisocyanate; hexamethylene diisocyanate',the diisocyanate derived from dimer acids; decamethylene diisocyanate,the reaction product of toluene diisocyanate with trimethylolpropane atan NCO/OH ratio of22l (Mondur CB), etc.

The polyisocyanate is usually employed in slight stoichiometric excessover the polyol so as to provide excess isocyanate linkages forcrosslinking with formation of biuret and allophanate linkages. Typicalisocyanate to hydroxyl group ratios are from 1.03 to l.25:l. On a weightbasis this represents a range ofapproximately 40 to 150 parts of polyisocyanate per 100 parts of polyol. Excess isocyanate will also react withany water, if present, to generate carbon dioxide which acts as ablowing agent to aid in forming a foam. The use of excess isocyanate aswell as the use of polyisocyanates having functionalities greater thantwo tend to provide foams which are more brittle.

The use of catalysts to assist in the formation of the polyurethanes isconventional and any of those known in the art may be employed in thepresent invention. Art especially ef fective catalyst is N,N,N',N'-tetrakis (Z-hydroxypropyl) ethylenediamine (sold under the tradenameQuadrol), because it is both catalytic, by virtue of its amino groups,and reactive with the polyisocyanate, by virtue of its hydroxyl groups.it acts, therefore, as a polyol, a catalyst and a cross linking agentand it becomes chemically incorporated into the polyurethane.

Other conventional catalysts that may be employed in polyurethanetechnology are N-methylmorpholine, N-ethylmorpholine, trimethylamine,triethylamine, tributylamine and other trialkylamines,triethylenediamines, tettamethylbw tylenediamine,3-diethylaminopropionamide, heat activated catalysts such astriethylamine citrate, 3-morpholinopropiona mide,2-diethylaminoacetamide, the esteriftcation product of l mole of adipicacid and 2 moles of diethylethanolamine, 3- diethylaminopropionamide,diethylethanolamine, triethylenediamine, N,N'dimethylpiperazine,N,Ndimethylhexahydroaniline. tribenzylamine and sodium phenolate; metalcompounds such as dibutyltin dilaurate, stannous chloride, dioctyltinoxide, stannous octoate, dibutyltin dioctoate, dibutyltin diacetate,chlorides of antimony, chlorides of titanium, chlorides of lead;especially the tin compounds herein set forth. If a conventionalcatalyst is employed, amounts of between 0.02 and 2.0 parts per 100parts by weight of polyol are desirable, but if Quadrol or any othercatalyst which becomes chemically incorporated into the polymer isemployed, much larger amounts, such as up to parts. are usuallydesirable.

The polyurethane is produced first in an intermediate fonn as a foam,preferably a rigid foam. This foam may be produced in accordance withthe practices well known in the foam art such as by the prepolymermethod, the semi-prepolymer (or quasi-prepolymer) method, or theso-called one-shot method. These are all well known methods of foampreparation. The semi-prepolymer method is generally considered to bemore reliable, but the one-shot method is clearly the more economical.Both of these latter two methods are especially suitable for manufactureof the foam from which absorbent material of the present invention maybe produced.

The preparation of a foamed polyurethane requires preparation ofpolyurethane in the presence of some means of blowing or expanding thepolymer material. One Well known foam-producing technique uses waterwhich reacts with excess isocyanate to produce carbon dioxide which thenacts as the blowing or expanding agent. One may also use nitrogen,carbon dioxide or other inert gases to provide the expansion. Whippingof air or other inert gas into the polymerizing mass may be used.

In accordance with a preferred method of the invention, it is desirableto employ a halogenated hydrocarbon, such as the fluorinatedhydrocarbons of the type sold under the trademarks Freor1 and Genetron".Among the fluorinated hydrocarbons which may be employed are those whichare sufficiently volatile to evaporate at the temperature of foamproductions. Desirably, the material shall have a boiling point slightlyhigher than ambient temperature. Among the satisfactory fluorinatedhydrocarbons which may be employed are trichlorofluoromethane,dichlorodifluoromethane, dichlorotetrafluoroethane,dichloromonofluoromethane, monochlorodifluoromethane,trichlorotrifluoroethane, and monochlorotrifluoromethane. Desirably,about 5 to 35 parts of blowing agent are employed per lOO parts ofpolyol.

Conventional surface active agents may be employed, especially thoseknown to polyurethane technologists, to help in nucleation and theformation of a more or less uniform, fine cell structure. These includethe silicones and particularly those known in the trade as L520,L530,L53l0, and L-5320 (Union Carbide) and DC-l99, DCl l3, DC-ZOl and DC202 (DowCorning). XI -i066 (General Electric) be lieved to be block copolymersof silicone and alkylene oxides. These are usually employed in amountsof up to l part per lOO polyol.

The rigid polyurethane foam is cured after formation by being permittedto stand at ambient temperature for at least about a day. Alternatively,the curing may be accelerated by the use of elevated temperatures, whichgenerally should not exceed C. During the curing treatment the foamloses its tackiness and develops its maximum rigidity.

After the formation of the polyurethane foam having preferably a bulkdensity of between 0.5 to 4.0 lbs/cuff, the foam is subjected to agranulation ope ration to produce granular particles substantiallydevoid ofcells and preferably having highly irregular physical shapes inthe form of jagged, spiny, cragged particles. The granulation isnormally conducted by grinding the foam. One preferred method ofgrinding is the use of a Pallmann grinder to reduce the foam to thedesired particle sizes.

After the grinding operation, it is desirable to subject the rigidpolyurethane particles to the action of water or steam. This is animportant step of a preferred embodiment of the process for preparingthe collector material. The temperature of the water of steam can rangefrom room temperature up to about C. Above 140 C there is dangerofdecomposing the product. During this treatment, considerable swellingof the granules takes place and it has been found that polyurethanesthus treated are more effective oil collectors than granules notsubjected thereto.

An optional inorganic material which may be employed in preparation ofthe polyurethane intermediate foam are the lower alkyl silicates, suchas those alkyl silicates containing up to four carbon atoms In the alkylgroup. Ethyl silicate is preferred. it is desirable to employ up toabout 5 parts of alkyl silicate per I00 parts of polyol.

In carrying out the process of removing oil from water in accordancewith a process of the present invention, the mixture of oil and watermay be slurried with the collector material or passed through one ormore columns packed with the collector material. In those instanceswhere the oil is spread over a large area of water, as may result fromsinking of an oil tanker or an accident in offshore drilling, thecollector material may be directly sprayed or poured on the oil surface,or permeable bags containing the collector material may be dumped on theoil. The collector material containing the oil can then be removedreadily by skimming or screening it from the surface of the water.

In carrying out the process of removing oil from sand in accordance withanother process of the present invention, the collector material iscontacted with the sand (with or without water). Separation is eflectedby floatation.

in carrying out the process of removing oil from a food product inaccordance with another process of the present invention, the collectormaterial may be slurried with the food product or the food product maybe passed through one or more columns packed with the collectormaterial.

The following are examples illustrating the preparation of collectorsfor oils in accordance with this invention, and the use of the collectormaterial in separating oil from water. The parts are by weight, unlessotherwise specified.

EXAMPLE I Step A A polyurethane foam was first manufactured from thefollowing materials:

100 parts of polyol (formed by the condensation of sorbitol withpropylene oxide, the condensation product having a hydroxyl number ofabout 490, available as G 24l0 from Atlas Powder Co., ChemicalsDivision, Wilmington,

Delaware);

76 parts of tolylene diisocyanate (a commercially available 80:20mixture ofthe 2,4 and 2,6 isomers);

25 parts of trichlorofluoromethane; and

0.5 to 1.5 parts oftriethylenediamine, as catalyst.

The catalyst was dissolved in the halogenated hydrocarbon, which wasadded to a mixture of the polyol and isocyanate and the mixture wassuitably agitated. Foaming began.

Upon completion of the foaming reaction, and when the mass became rigid,it was granulated to form irregularly shaped, spiny, jagged particles.The granular mass, having a mesh size in the range of 50-300 (U.S.standard mesh size), constituted material for preparation of thecollector material. Step B The granular mass produced in Step A wascontacted physically with an excess of Gulf Coast crude petroleum oiland water. The granular mass collected eleven times its own weight ofthe petroleum oil to produce a curd-like ag glomerated gel that wasseparated from the water by skimming and filtering through a wide meshleaving water essentially devoid of oil. A mixture of Gulf Coast crudeoil and water was passed through a permeable cartridge containing thegranular mass and the granular mass collected l 1 times its own weightof the petroleum oil. Similar results were obtained using animal andvegetable oils as well as refined GulfCoast petrole um products.

EXAMPLE 2 Step A The granular mass produced in Example 1 was washed withhot water at a temperature from 80 to 95 C. for about 3-5 minutes andfiltered The still moist granules were dried at atmospheric pressure ata temperature of 60 105 C. Step B The granular mass produced in Step Awas contacted physically with an excess of Gulf Coast crude petroleumoil and water. The granular mass collected 13 times its own weight ofthe petroleum oil to produce a curd-like agglomerated gel that wasseparated from the water by skimming and filtering through a wide meshleaving water essentially devoid of oil. A mixture of Gulf Coast crudeoil and water was passed through a permeable cartridge containing thegranular mass and the granular mass collected 13 times its own weight ofthe petroleum oil. Similar results were obtained using animal andvegetable oils as well as refined Gulf CoaSt petroleum products. Step CThe agglomerated gel produced in Step B was squeezed in a press and 7]percent of the oil was removed thereby. Substantially all of theremaining oil was recovered by washing the agglomerated gel with lightnaphtha. The collector was suitable for reuse both before and after thewashing with naphtha.

EXAMPLE 3 Step A 30 parts of the reaction product of pentaerythritolwith propylene oxide and having a hydroxyl number of 560 was mixed with[00 parts of tolylene diisocyanate (/20 mixture of the 2,4 and 2,6isomers). The temperature was not allowed to exceed C. and the reactionwas carried out under dry nitrogen gas. The product was allowed to cooland was stored in the absence of moisture. Step B A mixture was made of75parts of the polyol described in Step A, l0 parts ofN,N,N',N'-tetra-kis (hydroxypropyl) ethylene diamine, 3 parts of a 30percent aqueous solution of sodium tungstate, 2 parts of ethyl silicate,0.3 part of a 30 percent aqueous solution of triethylene diamine, l5parts of trifluorochloromethane, and 0.5 part of a urethane-gradesilicone surface active agent (L-520 of Union carbide). Step CApproximately equal weights of the products from Step A and Step B weremixed thoroughly and poured into a mold. The resulting foam was a white,fine-celled material which was allowed to cure for a day at roomtemperature. The resulting foam was granulated in a Pallmann mill, andthe resulting particles treated with water for about 15 minutes at aboutC. followed by about a half hour at 80 l00 C. The white granules werethen dried in an oven at l05 C. The fraction smaller than 840 micronsparticle size and larger than 177 microns particle size was collected.The product consisted of particles with a spiny, cragged, irregularshape devoid of cellular structure. Step D The granular mass produced inStep C agglomerated 15 times its own weight ofGulf Coast crude oil andabout 70 percent thereof was removed by pressing.

EXAMPLE 4 Example 3 was repeated, employing instead of tolylenediisocyanate an equivalent weight of methylene diphenyl diisocyanate.The result was a collector material having equivalent properties tothose of the product of Example 3. The granular mass agglomerated 13times its own weight of Gulf Coast crude oil.

EXAMPLE 5 Example 3 was repeated, but employing an equivalent amount ofa mixture of glycerol and tetrol instead of sorbitol. The resultingcollector material was similar in its properties to the product ofExample 3. The granular mass agglomerated 12 times its own weight ofGulf Coast crude oil.

lclaim;

l. A method for removing oil from a mixture of oil and water; the methodcomprising the steps of:

contacting the mixture with a collector comprising granules of rigidpolyurethane having jagged, spiny, cragged forms, said granules beingsubstantially devoid of cellular structure and having a particle sizebetween 50 and 750 microns; removing mechanically the collectorcontaining the oi! from the water.

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